Sorry but I am getting close and want to be on the road not in the shop.
Any thoughts or ideas are welcome. I will sort them all out.
Arch,
1. Cloyes true roller timing chains are the best. Period. That's why
racers use them. I bet your friend is is running a roller cam with 3
times the valve spring pressures as a stock 455 has. Go with the
Cloyes!
2. Three angle valve grinds are the industry standard for any valve
job.
3. Perfect Circle (PC) positive valve seals are a must. Most GMC's
operate with up to a quart of oil floating around in the valve covers.
Have the cylinder heads done by a reputable shop that will clearance the
the heads for the better seals if necessary.
4. Severe Duty Manley stainless steel valves are superb replacements.
Beware of deals on other brands. There are good deals on off brands but
most are made in Australia, Israel, etc. I had a single valve bind in
the guide (took out a piston) & when we checked the stems we found a
wide tolerance on the stem dimensions. I paid for that mistake, why
should anyone else?
5. While you're in there, change out the springs, keepers & retainers.
Small investment for a vital items that take quite a beating.
6. There'll probably be some discussion on this but I do not use bronze
quides. For stock to mild performance rebuilds I always use cast iron
guides. I also prefer Competition Engineering roller tipped rockers as
the tips roll across the top of the valve when opening & closing & I
believe this tends to exert less side pressure from the stem on the
guides. I ran a pair for 30,000 miles & pulled the heads for a
freshening up & the shop owner commented on how the tips of the valves
still looked perfect, as in no mushrooming. Also, don't forget that the
stock ones managed to last well over 100,000 too. Don't reuse the
originals, replace them with Pioneer, Eglin, Manley etc. They're all
good.
7. Don't worry about what cam grinds are used for racing applications.
You can call Competition Engineering tech line (& any other reputable
camshaft manufacturer)& tell them what your application is, operating
rpm etc. & they will have a recommended grind & installation procedure
for you. I'm not sure, but I think Mondello gets his camshafts from
CE. I've never heard of a core charge for a camshaft. (Some will give
you a few bucks for your old one if it can be reground.) I buy a ton of
camshafts from Schneider Cams & about twice a year when the pile gets
too high, I give them all my used ones. The lifters must be replaced
with a new camshaft! There are only about 4 companies left making them
in the US & Johnson is the best. I believe they're the GM OEM
manufacturer.
8. If you have any questions call Greg Larsen at Cylinder Head Services
at (619)295-1371. Cylinder heads are and have always been his life.
9. (This is getting a bit "rambly") When the manufacturer made the
crank & other internal components they had tolerances to adhere to.
Frinstance, + or - 2 deg. on the crank keyway, +or _ 2 deg on the cam
dowel, balancer keyway, lobes etc. You get the picture. If you happen
to be unlucky enough to get an engine wherein all of these tolerances
are max on one side or the other, you wind up with an engine that just
won't perform up to design specs. This is where blueprinting comes in &
why guys like Mondello, GES, Ed Hale, etc. can do a stock rebuild that
outperforms other stock rebuilds. With the heads off, use a dial
indicator & find true TDC & mark your balancer. Use this reference when
degreeing in your camshaft to the specs the cam manufacturer gives you
on the installation guide. Don't just install the cam & line up the
crank & cam gear marks. Use a degree wheel & do it right. There's more
on this that deals with timing chain stretch, advancing or retarding the
cam and other installation procedures. Too much for here and probably
overkill for our purposes.
HTH,
Steve Ferguson
San Diego
Any thoughts or ideas are welcome. I will sort them all out.
Arch,
1. Cloyes true roller timing chains are the best. Period. That's why
racers use them. I bet your friend is is running a roller cam with 3
times the valve spring pressures as a stock 455 has. Go with the
Cloyes!
2. Three angle valve grinds are the industry standard for any valve
job.
3. Perfect Circle (PC) positive valve seals are a must. Most GMC's
operate with up to a quart of oil floating around in the valve covers.
Have the cylinder heads done by a reputable shop that will clearance the
the heads for the better seals if necessary.
4. Severe Duty Manley stainless steel valves are superb replacements.
Beware of deals on other brands. There are good deals on off brands but
most are made in Australia, Israel, etc. I had a single valve bind in
the guide (took out a piston) & when we checked the stems we found a
wide tolerance on the stem dimensions. I paid for that mistake, why
should anyone else?
5. While you're in there, change out the springs, keepers & retainers.
Small investment for a vital items that take quite a beating.
6. There'll probably be some discussion on this but I do not use bronze
quides. For stock to mild performance rebuilds I always use cast iron
guides. I also prefer Competition Engineering roller tipped rockers as
the tips roll across the top of the valve when opening & closing & I
believe this tends to exert less side pressure from the stem on the
guides. I ran a pair for 30,000 miles & pulled the heads for a
freshening up & the shop owner commented on how the tips of the valves
still looked perfect, as in no mushrooming. Also, don't forget that the
stock ones managed to last well over 100,000 too. Don't reuse the
originals, replace them with Pioneer, Eglin, Manley etc. They're all
good.
7. Don't worry about what cam grinds are used for racing applications.
You can call Competition Engineering tech line (& any other reputable
camshaft manufacturer)& tell them what your application is, operating
rpm etc. & they will have a recommended grind & installation procedure
for you. I'm not sure, but I think Mondello gets his camshafts from
CE. I've never heard of a core charge for a camshaft. (Some will give
you a few bucks for your old one if it can be reground.) I buy a ton of
camshafts from Schneider Cams & about twice a year when the pile gets
too high, I give them all my used ones. The lifters must be replaced
with a new camshaft! There are only about 4 companies left making them
in the US & Johnson is the best. I believe they're the GM OEM
manufacturer.
8. If you have any questions call Greg Larsen at Cylinder Head Services
at (619)295-1371. Cylinder heads are and have always been his life.
9. (This is getting a bit "rambly") When the manufacturer made the
crank & other internal components they had tolerances to adhere to.
Frinstance, + or - 2 deg. on the crank keyway, +or _ 2 deg on the cam
dowel, balancer keyway, lobes etc. You get the picture. If you happen
to be unlucky enough to get an engine wherein all of these tolerances
are max on one side or the other, you wind up with an engine that just
won't perform up to design specs. This is where blueprinting comes in &
why guys like Mondello, GES, Ed Hale, etc. can do a stock rebuild that
outperforms other stock rebuilds. With the heads off, use a dial
indicator & find true TDC & mark your balancer. Use this reference when
degreeing in your camshaft to the specs the cam manufacturer gives you
on the installation guide. Don't just install the cam & line up the
crank & cam gear marks. Use a degree wheel & do it right. There's more
on this that deals with timing chain stretch, advancing or retarding the
cam and other installation procedures. Too much for here and probably
overkill for our purposes.
HTH,
Steve Ferguson
San Diego
